Film making and in particular camera movement has heretofore been a skilful but imprecise art. Particular types of film making techniques require particular regard be devoted to highly accurate motion control of the image recording camera with the added necessity for the motion to be repeated many times to an equivalent degree of accuracy.
These types of motion requirements are determined by aesthetic and technically practical reasons. In particular the increasing use of digital graphics to enhance and enliven real world film images requires particular regard be devoted to highly accurate motion control of the image recording camera. To enable the digitally created images to appear to interact with the recorded real world film and video image, it is necessary that
(a) the digital image is in perspective with the surrounding image;
(b) the digital image has the same colour, hue and lighting as that in the surrounding image; and
(c) the digital image has a 3-dimensional shape which orientates itself according to the perspective provided by the image recording camera's position.
Only with highly accurate and repeatable camera motion can real world image recording be achieved to the accuracy required, and further by recording camera motion characteristics at the time, information necessary for constructing the digital graphics be achieved such that the real and digital images seemlessly interact.
Highly accurate and repeatable control of camera movement is also required for those situations where only a remotely controlled camera can be placed.
Therefore motion control is an electronic and mechanical technique that allows the physical motions of a camera and/or other objects in a scene to be recorded or preprogrammed with sufficient accuracy to make repetitions of those motions that exactly match each other and that then allow integration of digital graphics into the images recorded. It is a further desirable aspect of motion control that the control provided be as realistic as possible and that since the camera is under machine control the artistic demands that can only be achieved by real time motion are available to the camera operator.
As an example of real-time motion recording techniques, actors can be made to look like they are interacting with miniatures which are actually composited into the real-time scene at a later time. A camera used to record a real-time scene must be able to pan, tilt, track, crane, etc, freely as they would ordinarily do so but done in such a way that allows their motion to be plotted in an effects studio to create a basis for a digital motion file of the real-time scene and which in turn is used to create corresponding and interactive miniature model movement. By re-recording the scene without actors with miniatures or digitally animated characters created and viewed from the exact camera positions of the real-time recording the finished view seemlessly brings together the two disparate objects. This has heretofore been a cumbersome and time consuming process having inaccuracies caused by poor control equipment and techniques which ultimately degrade the quality of the result.
In addition to the above, camera motion especially that which is required to be preprogrammed cannot, even with the existing technology of motion control be provided with movement characteristics which mimic the effects of controlled vibration and damped oscillations as are experienced by real-life cameras under human control. Some special effects require fine camera movement during larger camera manipulation. This is especially so since this characteristic of camera manipulation cannot be accurately repeated even by highly skilled human operators but which is often required for the purposes of creating special effects.
As well as the above, much contemporary motion control filming is done using stop-motion techniques which comprise the filming of special effects, frame by frame. Between frame exposures, the subject is moved in a controlled fashion while generally the background scene is kept stationary. Only a stationary background can provide a suitable reference for the moving object, otherwise, moving the camera and thus the background along with the object requires a high degree of co-ordination not normally available in the studio and particularly not in the field.
Old film recording methods to enable real-time and stop-motion techniques of film recording to matte with computer generated graphical objects and scenes include the use of "witness points" (optical targets) to serve as reference marks for use by the post production operators. "Witness points" are tracked by special software designed to simulate the imaginary camera motion and then compensate for the optical distortion characteristics of particular lenses being used during real-time recording so that computer graphics generators or illustrators can have references to work with when creating the animation that is required for the matte of real-life with animated characters.
This method evolved because of the present inability of camera and motion control equipment to provide the required information to the post-production and computer graphics area.
Ideally, the moving camera should record the background scene in the same relative position on the frame with every repetition of the camera motion. This cannot be achieved if camera motion is not accurately repeatable nor can the time scale of the scene be adjusted.
Computer controlled camera motion devices would assist cinematographers because it allows controlled and repeatable motion of the camera and coincident control of the film pull down rate to adjust the time scale of the scene.
Highly accurate camera motion control is equally important for real-time special effects recording where the cinematographer invariably wishes to exercise a greater degree of artistic and aesthetic control of the motion at the time of recording and thereafter allow greater flexibility at the post-production stage.
The object of achieving highly accurate camera motion control has been the subject of some endeavour and generally has had little commercial success due mainly to impractical arrangements and configurations of equipment.
Typically large, rigid, bulky and heavy camera platforms have been used because high inertial mass platforms provide stability for the camera. It has been found however that these devices are difficult to accelerate and decelerate to the required speeds of real-time action and very difficult to relocate out of their normally studio-bound domain.
This invention however achieves this objective by providing a motion control platform that uses low mass components which have low inertia. What results is a motion controlled platform to provide motion for a camera which itself is controlled to orientate and which achieve high articulation speeds but which is also easily transportable and reconfigured.
With a configuration of this type the camera platform may with the aid of suitably located tracks provide studio, and location filming at any desired orientation of the camera platform. For example the camera may be made to climb walls or operate suspended from a ceiling while moving along the tracks.
It has been a further problem of prior motion control devices that although assisted by the programmed control of a computer, the operation of all such prior art arrangements is hampered by the serial nature of the processing power of the computer. This means that although there are a myriad of camera and platform motion devices to be controlled, for example forward motion of the camera platform during a tilting and panning motion of the camera itself, the computer may only comfortably control one or two of those motions at a time.
Attempts to alleviate this problem include using faster computers and more time-efficient code so as to sequence these control events in such a manner that the tasks are seemingly concurrent. The limits to these arrangements have been reached and thereby impinge upon the ability of the system to support the creative and technical needs of cinematographers.
Prior attempts to provide motion control equipment have also disregarded the all important post-production requirements which ideally require certain data capture at the time of image recording. This data comprises all the facets of the motion and camera orientation control sequence and other characteristics such as focus settings, lens zoom settings, light levels, film frame pull down rates, camera heights, frame synchronisation signals with special emphasis on pan, roll, tilt and position of the camera along its tracks. This type of data is particularly important to the computer graphics creator at graphic design, matte and post production stages.
The computer graphics creator needs these details to ensure that the graphical computer generated objects created for the scene are proportioned and maintain the appropriate proportion as the film/video image, especially the background, changes. Further, the data which forms the object database needs then to have texture, reflectance, transparency and colour added to its surfaces. To these details are added further creative visual factors such as lighting, shading and visual mood elements which may include lighting effects that cannot exist in the real world. These effects are then stored as a scene file that will control the look of the final film scene.
Therefore it is a desirable feature of this invention that the system provides a means to programme, modify and repeat the control and motion of a camera while being able to vary scene characteristics such as object placement, lighting, effects enhancement, scaling changes of models and background motion.
It is also desirable that the camera motion provided is smooth and accurately repeatable.
It is further desirable that the system provided is transportable and easily reconfigured and importantly that features associated with the system can be enhanced and increased in a modular way.
It is yet a further feature of the system provided, that it allows operator control of the camera motion to the extent that a variety of motions can be superimposed over the preprogrammed motion.
In order that the invention may be clearly understood and readily carried into effect, an embodiment will now be described by way of example only, with reference to the accompanying representations, wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a remote control console;
FIG. 2 depicts a graphical user interface to provide instructions to the motion control apparatus;
FIG. 3 depicts block diagram of the motion control apparatus;
FIG. 4 depicts a schematic of the curve generator and signal processing module of the motion control apparatus;
FIG. 5 depicts a schematic of the motion control apparatus;
FIG. 6 depicts a dolly and camera control platform;
FIG. 7 depicts a schematic of the dolly drive and stabilisation rollers in end elevation;
FIG. 8 depicts a schematic of the dolly drive and stabilisation rollers in plan view as seen without a motor and drive pulley in place;
FIG. 9 depicts a schematic of the dolly drive and stabilisation rollers in elevation view;
FIG. 10 depicts a jib arm mounted on a dolly drive platform; and
FIG. 11 depicts a telescopic arm suspended from a gantry.